This invention relates generally to automated handling of drums or cans and more particularly to a palletizer for moving a plurality of stacked cans from a first pick-up position on a conveyor to a second deposit position on a pallet.
Chemical products in liquid form, such as herbicides, insecticides, oil, grease, and other chemicals, are often packaged and sold in five gallon drum containers. The five gallon drum containers or cans are generally cylindrical in shape with a flat top and bottom. A folddown handle is generally provided in the middle of the top of the can and a circular opening for filling and emptying is also provided in the top adjacent the edge of the can.
In an automated process the cans are moved in serial fashion by a can conveyor to a filling station then to a capping station where the cans are sealed. Once the cans have been filled and sealed, the cans are stacked one on top of the other and a group of the stacked cans are then placed on a pallet in order to facilitate the handling of the cans by mechanical means during warehousing and shipping.
The prior art provides a means for stacking cans one on top of the other, generally three in height, as the cans come from the capping station. Once the cans have been stacked three high on the conveyor, some means must be provided for accumulating a group of the stacked cans and transferring them from the conveyor to the pallet on which they will ultimately be stored and handled.
The problem of picking up a group of stacked cans from a conveyor and transferring them to a pallet is complicated by the weight of the filled cans, the variation in height of the individual cans and the unevenness or skew of the flat tops and bottoms of the individual cans. For example, if the bottoms and tops of the cans are skewed, the three stacked cans may tend to be somewhat unstable and tip when picked up from the conveyor by any mechanical means. The possibility of a five gallon can weighing 40 lbs. or more toppling from a conveyor or a palletizer presents an extremely hazardous situation in the handling of these cans. This hazard is greatly increased when the cans are filled with toxic or flammable fluids which may be released if the cans fall and are ruptured.
It is also desirable in putting five gallon cans onto a pallet to provide for either straight stacking, i.e. each row on the pallet contains the same number of cans or for staggered stacking, i.e. every other row contains one less can than the adjacent row so that the cans nestle into the intervening space between the adjacent rows.
It is therefore an object of the present invention to provide a palletizer which can accumulate a number of stacks of cans on a can conveyor, lift those cans from the conveyor in a steady and stable fashion, transport the cans from the conveyor to a pallet and deposit the cans onto the pallet.
Collaterally then, it is an object of the present invention to provide a palletizer having carriage means mounted on a frame which moves between a first pick-up position adjacent the can conveyor to a second deposit position adjacent the pallet.
More particularly, it is an object of the present invention to provide carriage means which includes lift means and hold-down means which together cooperate to lift the cans from the conveyor while simultaneously holding them firmly so as to eliminate the risk of the stacked cans toppling while the carriage means moves from the first pick-up position to the second deposit position.
It is also an object of the present invention to provide unloading means on the carriage means which when the carriage means is adjacent the pallet, the unloading means serves to push the cans off of lift means and to snug the cans against the other cans on the pallet.
It is further an object of the invention to provide can guide means adjacent to the conveyor to align the cans on the conveyor prior to the lift means engaging the cans at the first pick-up position to assure adequate engagement of the cans by the lift means.
It is further an object of the present invention to provide hold-down means that will engage the can tops so as to pull them toward the carriage means thereby assuring stability.
It is also an object of the present invention to provide accumulator means having a counter which controls the number of stacks of cans accumulated so that staggered stacking on the pallet can be accomplished.